1. Field of the Invention
The present invention relates to a lightweight, nonmotorized antenna system specially adapted for use on a boat or ship.
2. Description of Prior Art
Radar is widely used on both commercial and pleasure water craft of all sizes and motive means. Regardless of the type or size of the vessel, all marine radar sets are composed of the same basic building blocks, namely: the display, the data processing unit, the transceiver, and the antenna unit. One example of such a known marine radar set is shown in FIG. 1. In operation, the data processing unit 6 creates an electrical signal that is fed to the transceiver 8, and the transceiver 8 then feeds the signal through a coaxial cable 10 and a rotary joint 12 to the antenna 14. This signal is radiated from the antenna 14 in the form of an electromagnetic wave that propagates away from the antenna 14 until it encounters a solid object and is reflected. The antenna 14 then intercepts the reflected electromagnetic wave and converts it back into an electrical signal, which is fed back through the rotary joint 12 and the coaxial cable 10 to the transceiver 8. The transceiver 8 then communicates to the data processing unit 6 that the reflected signal has been received and the data processing unit 6 computes the distance and bearing of the solid object causing the reflection and produces information to be displayed on the display screen 16. Conventional marine radar antennas, such as antenna 14 in FIG. 1, are mounted on motorized mounts 18 that rotate the antenna in order to effectuate circular coverage. When such motorized mounts are employed, the resulting antenna/mount unit is substantially heavier than the antenna by itself. Nevertheless, these marine radar antennas must still be mounted as high as possible in order to maximize the range of the radar set.
Therefore, not only does the added weight of the motorized mount present a hazard and danger to the installer when the antenna unit is being mounted high upon a mast or support structure, but the extra weight of the motorized mount on its support structure can produce unnecessary, uncomfortable, and possibly even dangerous rolling motion upon the vessel.
Additionally, because motorized mounts are exposed to the elements, they are liable to rust and wear, especially when used in a high humidity environment as is encountered on the water. Such rust and wear inevitably result in requiring frequent preventive and corrective maintenance.
Finally, and significantly, when these motorized mounts are mounted to the mast of a sailboat, they are by necessity mounted either in front of, behind, or to the side of the mast. When positioned in this manner, the mast blocks radar coverage in a given segment of space. As shown in FIG. 2, mast 20 is mounted upon deck 22 of a vessel and motorized antenna 27 is mounted on horizontal member 23 in front of mast 20. Blind area 25 represents the segment of space that can not be scanned by motorized antenna 27.